Etymology From Old French rationel, rational, from Latin rationalis (“of or belonging to reason, rational, reasonable; having a ratio”), from ratio (“reason; calculation”).
The utility of valid arguments is a monument to our frailty: to the fact that we are not completely rational beings.2001, Mark Sainsbury, chapter 1, in Logical Forms — An Introduction to Philosophical Logic, 2nd edition, Blackwell Publishing, →ISBN, §7, page 32:
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Economics, Sciences Behaving according to some partial order of preferences.
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Logically sound; not self-contradictory or otherwise absurd.
His statements were quite rational.
Prevention for the future is now almost universally allowed to be the only rational plea for the infliction of punishment; but this, when left to the arbitrary discretion of individuals, always has been found, and always will be found, to degenerate into the exercise of revenge for the past.1812 The Freethinking Christians' Magazine: Volume 2 p. 21
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Healthy or balanced intellectually; exhibiting reasonableness.
Of a person or personal characteristics
rational conduct
Temperature 99.8 degrees. Pulse 104. She was quite conscious and rational at times, at others very noisy.1867 C. Handfield Jones, Case Of Low Fever: Delirium: Incomplete Dementia. The British Medical Journal Vol. 2, No. 344, Aug. 3
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The [Isaac] Newton that emerges from the [unpublished] manuscripts is far from the popular image of a rational practitioner of cold and pure reason. The architect of modern science was himself not very modern. He was obsessed with alchemy.2014 June 21, “Magician’s brain”, in The Economist, volume 411, number 8892:
› Comprising, or expressible as, a ratio
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Arithmetic, Mathematics, Sciences Of a number, capable of being expressed as the ratio of two integers.
¾ is a rational number, but √2 is an irrational number.
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Algebra, Mathematics, Sciences Of an algebraic expression in indeterminates, or more generally a function: capable of being expressed as the ratio of two polynomials.
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Algebraic geometry, Geometry, Mathematics, Sciences Of a variety: (informally) geometrically simple almost everywhere; (formally) birationally equivalent to projective space
Algebraic geometry, Geometry, Mathematics, Sciences Of a point on an algebraic variety over a field: whose coordinates belong to the field in question (in contrast to those points of the variety which are only defined over the algebraic closure of the base field).
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Chemistry, Natural sciences, Physical sciencesObsolete synonymous replacement for "condensed" in condensed formula.
Etymology From Old French rationel, rational, from Latin rationalis (“of or belonging to reason, rational, reasonable; having a ratio”), from ratio (“reason; calculation”).
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Mathematics, Sciences A rational number: a number that can be expressed as the quotient of two integers.
The quotient of two rationals is again a rational.
rational
noun
Etymology From Old French rational, from Medieval Latin rationale (“a pontifical stole, a pallium, an ornament worn over the chasuble”), neuter of Latin rationalis (“rational”), for which see the first etymology. Translation of λογεῖον (logeîon) or perhaps λόγιον (lógion, “oracle”) in the Septuagint version of Exodus 28.
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Historical The breastplate worn by Israelite high priests.
The Rationale of iudgement alſo thou shalt mke with embrodered worke of diuers colours, according to the workmanship of the Ephod of gold, hyacinth, and purple, and ſcarlet twiſe died, and twiſted ſilke.1609, The Holie Bible, […] (Douay–Rheims Bible), Doway: Laurence Kellam, […], →OCLC, Exodus 28:15, page 234: